WO2002022757A1

WO2002022757A1 - Dispersion for preventing electrification and antistatic film, and image display device

Info

Publication number: WO2002022757A1
Application number: PCT/JP2001/007863
Authority: WO
Inventors: Takeo Ito; Tsuyoshi Oyaizu; Akira Mikami; Hitoshi Tabata
Original assignee: Kabushiki Kaisha Toshiba
Priority date: 2000-09-11
Filing date: 2001-09-11
Publication date: 2002-03-21
Also published as: EP1323804A4; EP1323804A1; KR20030041989A; US6992431B2; US20040058148A1; CN1454250A; CN1282726C; KR100534508B1; JP2002080828A; TWI221622B

Abstract

A dispersion for preventing electrification, characterized in that it contains, as a primary component, high-resistance particles having a resistivity of 10?6 to 109¿ Φ.cm. The application of the dispersion by a simple and easy method such as spray coating or brushing followed by firing can provide an antistatic film having stable antistatic properties, since the resultant antistatic film exhibits a reduced dependency of electric resistance on the sickness of a film and on environmental conditions. Such high-resistance particles include antimony pentoxide (Sb¿2?O5) particles having a pyrochlore crystal structure, and particles having a core layer of at least one semiconductive substance selected from among SnO2, In2O3, and Sb2O5 and ZnO2 and a covering layer of at least one insulating substance selected from SiO2, TiO2, Al2O3 and ZrO2. An image display device which has insulating members, arranged in a vacuum envelope, having the above antistatic film formed on the surface thereof is free from the deterioration of display characteristics caused by the change of the track of electrons emitted by the application of voltage, or by a spark in a tube or a leakage current, and accordingly exhibits stable and good display characteristics.

Description

Dispersion for antistatic, antistatic film, and image display device

Technical field

The present invention relates to an antistatic dispersion and an antistatic film, and to an image display device such as a color cathode ray tube and a field emission display (FED) provided with the antistatic film. Light

Background technology

Conventionally, in a cathode ray tube (CRT), charging is caused by a part of the electrons emitted from the electron gun hitting the inner wall of the neck, or by the ionization of the ions emitted by the emitted electrons. . For this reason, an antistatic film is formed on the glass substrate on the inner wall of the neck in order to prevent the trajectory of the emitted electrons from being bent due to charging, and preventing the electrons from reaching the normal position on the phosphor. ing.

As a material for forming such an antistatic film, conventionally, a specific resistance value (resistivity) such as IT 0 (Indium-Tin-Oxide), ATO (Antimony-Tin-Oxide), or Zn ₂ There 1 0 ⁵ Omega · cm or more semiconductive substance particles are used.

Further, a surfactant or quaternary § Mi emissions, either added during the S i 0 _2, by some have the be coated on S i 0 ₂ film, is generally known a method of imparting ionic conductivity I have.

However, such an antistatic film is not sufficiently satisfactory as an antistatic film provided on an insulating member disposed in a vacuum envelope, such as an inner wall portion of a neck of a color cathode ray tube. Was. That is, antistatic Tomemaku consisting semi-conductive fine particles such as ITO or ATO, since a large film thickness dependency of the resistance value (surface resistance) is the most preferable range of the surface resistance value 1 0 ^{1 ( ) To} control the thickness to 010 ¹² Ω / cm ² , it was necessary to control the film thickness extremely accurately. In addition, it is difficult to precisely control the thickness of the antistatic film by using a spray coating method or a brush coating method. The antistatic film was formed using the method. In addition, even when using the dipping method or the spin coating method, it is necessary to strictly control the film thickness, and there is a problem that the trouble of the film thickness control and the production cost are large.

Furthermore, the ion conductive film that has been used conventionally has a small dependence of the resistance value on the film thickness, but has a large dependence on the environment such as temperature and humidity. It could not be used as an antistatic film.

The present invention has been made to solve these problems. Since the resistance value has a small dependency on the film thickness and also has a small dependence on the environment such as temperature and humidity, the charging device has stable antistatic characteristics. An object of the present invention is to provide an antistatic film, a dispersion capable of forming such an antistatic film by a simple coating method, and an image display device provided with the antistatic film. Disclosure of the invention

A first aspect of the present invention, as described in claim 1, characterized in that it contains a high resistivity particles having a specific resistance of ^{^{1 0 6 ~ 1 0 9 Ω}} · cm as a main component charged It is a dispersion for prevention.

By using this antistatic dispersion, the resistance (surface resistance) has a small dependence on the film thickness, as well as a small environmental dependence, and a stable charge. An antistatic film having antistatic properties can be formed by a simple method.

When specific resistance of the high resistance fine particles in the dispersion is less than 1 0 ⁶ Ω · cm is made that the resistance value of the antistatic film obtained from the dispersion is highly dependent on the film thickness, spray coating (4) A low-cost and simple method such as brush coating cannot provide an antistatic film having a desired stable resistance value. Conversely, 1 when a 0 exceeds ⁹ Omega · cm using a fine particle having an inherent resistance value is not a film having a sufficient antistatic property can be obtained.

In the antistatic dispersion according to the present invention, as described in claim 2, the high-resistance fine particles are formed of antimony pentoxide having a pyrochlore-type crystal structure.

May be (S b ₂ 0 _5). Pyrochlore type crystals are cubic

(Equiaxed) The crystal structure is high and the symmetry of the crystal is high, so the effect of crystal orientation on the transfer of carrier electrons in the polycrystalline state is small. Further, since electrical resistance of the grain boundary is low, it is possible to obtain a high resistance particles having a specific resistance of ^{^{1 0 6 ~ 1 0 9 Ω}} · cm easily.

Further, as described in claim 3, the high-resistance _{fine, S n 0 2, I n} 2 0 3, S b 2 0 5, Z n 0 at least selected from ₂ semiconductive one substance a core layer consisting of, the core layer periphery formed _{of, S i 0 2, T i} 0 2, a 1 2 0 3, Z r 0 _both least selected from consisting of one insulating material coating And a layer. Even in fine particle having such a structure, it is possible to easily realize a specific resistance of ^{^{1 0 6 ~ 1 0 9 Ω}} · cm.

Further, as described in claim 4, the particle diameter of these high-resistance fine particles can be 5 to 10 Onm.

A second aspect of the present invention, as described in claim 5, an antistatic film formed on the surface of the insulating substrate to be held in a vacuum atmosphere, 1 0 ⁶ -1 It is characterized by being composed mainly of high-resistance fine particles having a specific resistance of ⁰⁹ Ω · cm.

In this antistatic film, as described in claim 6, the high-resistance fine particles may be an antimony pentoxide having a crystal structure of pyrochlore (S b ₂ 0 _5). Further, as described in claim 7, the high-resistance fine particles, consisting of _{S n0 2, I n 20 as} S b 2 0 5, Z n0 least for the at one semi-conductive material selected from the _second core having a layer, the formed outer periphery of the core layer, the S i 0 _2, T I_〇 _2, a 1 ₂ 0 _3, Z R_〇 coating layer consisting of at least one insulating material selected from ₂ The high-resistance fine particles may have a particle size of 5 to 10 O nm, as described in claim 8.

Since the antistatic film of the present invention has a small dependence of the surface resistance value on the film thickness, it is not necessary to control the film thickness precisely, and therefore, the antistatic film can be formed by a simple method such as spray coating and brush coating. Can be. Here, the relationship between the film thickness and the resistance value (surface resistance value) of each of the antistatic film of the present invention and the conventional antistatic film composed of fine particles of ITO or ATO is schematically shown in FIG. Show. The antistatic film of the present invention has a smaller dependence of the resistance value on the film thickness as compared with the conventional antistatic film, and the width (range) of the film thickness at which a desired resistance value is obtained is wider.

Further, since the antistatic film of the present invention has a stable resistance value and low environmental dependency of the resistance value, it can be used in a vacuum atmosphere such as inside a vacuum tube. In other words, not only as an antistatic film on the inner wall of the neck of a color cathode ray tube but also as an antistatic film on an insulating member such as a spacer in a field emission display (FED). It can be widely used as an antistatic film for products. According to a third aspect of the present invention, as described in claim 9, a translucent panel is provided. A vacuum envelope whose inside is held in a vacuum, a phosphor layer formed on the inner surface of the translucent panel, and electron emission means arranged inside the vacuum envelope. An image display device, comprising: an insulating member according to claim 5 on a surface of an insulating member disposed in the vacuum envelope. As described in 0, the thickness of the antistatic film is desirably 50 to 100 nm. Further, as described in claim 12, it is desirable that the antistatic film be configured to cover 20% or more of the entire surface area of the insulating member disposed in the vacuum envelope.

In the image display device of the present invention, the surface of the insulating member disposed in the vacuum envelope has a small dependence of the resistance value on the film thickness and environmental conditions, and has a stable antistatic property having a desired resistance value. Since the film is formed, good display characteristics are exhibited without the occurrence of orbital deformation of emitted electrons due to the application of voltage, spark in the tube, or deterioration of display characteristics due to leak current. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graph schematically showing the relationship between the film thickness and the surface resistance value of the antistatic film of the present invention and the conventional antistatic film, respectively.

FIG. 2 is a sectional view showing a schematic configuration of the antistatic film of the present invention, and FIG. 3 is a sectional view showing a schematic configuration of a color cathode ray tube which is a first embodiment of the image display device of the present invention. Yes,

FIG. 4 is a sectional view showing a schematic configuration of an FED which is a second embodiment of the image display device of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the present invention will be described. Note that the present invention It is not limited to the following embodiment.

FIG. 2 is a sectional view showing a schematic configuration of the antistatic film according to the present invention. In this figure, reference numeral 1 denotes an insulating substrate which is held in a vacuum atmosphere, and on the surface thereof, the high resistance that Yusuke 1 0 ⁶ -1 0 resistivity of ⁹ Omega · cm (the resistivity) An antistatic film 2 made of conductive fine particles is formed.

Such antistatic layer 2, a high-resistance fine particles having a specific resistance of ^{^{1 0 6 ~ 1 0 9 Ω}} · ο m, added and mixed in a solvent, a liquid prepared by dispersing (min dispersion liquid) Is applied to the insulating base material 1, dried, and then fired at a temperature of 400 ° C. to 500 ° C. Examples of the solvent include alcohols such as methanol, ethanol, and isopropyl alcohol; ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; ethylene glycol, propylene glycol, and hexylene glycol. Organic solvents such as glycols and heterocycles such as tetrahydrofurfuryl alcohol and N-methylpyrrolidone can be used. A known dispersant can be added to these solvents.

The high-resistance fine particles having a ^{^{1 0 6 ~ 1 0 9 Ω}} ■ resistivity of cm, can be used antimony pentoxide having a crystal structure of pyrochlore (S b ₂ 0 _5). Further, the outer periphery of the S nO There _{_{_{ln 2 0 3, S b 2}}} 0 5, Z n0 at least selected from ₂ one semiconductive core layer _{material, S i 0 2, T i} 0 2, A 1 ₂ 0 _3, Z r 0 at least selected from ₂ can be used one kind of insulating fine particles of the coating layer formed structure of matter Ru.

It is desirable that the particle diameter of these high resistance fine particles be 5 to 100 nm. If the particle size is less than 5 nm, the workability in applying the dispersion is poor, and it is difficult to obtain an antistatic film having a desired film thickness as described below. Anti On the other hand, when the particle size exceeds 100 nm, the film formability is poor and the uniformity of the antistatic film is deteriorated, which is not preferable.

As a method for applying the dispersion, a simple method such as a spray coating method and a brush coating method can be employed in addition to the dip coating method and the subbing method.

Furthermore, in this way to control the most preferred range of the surface resistance of the antistatic film formed ^{(1 0 1 ° ~ 1 0} 1 2 Ω Ζ cm 2), thickness of the antistatic film 5 0-1 0 Desirably, it is 0 O nm. If the thickness of the antistatic film is less than 5 O nm, the surface resistance becomes too high and desired antistatic properties cannot be obtained. Conversely, if the film thickness exceeds 100 nm, the surface resistance becomes too low to obtain the desired antistatic properties, and the film tends to crack.

Further, the coverage of the antistatic film 2 is desirably 20% or more of the entire surface area of the insulating substrate 1 held in a vacuum atmosphere. If the coverage of the antistatic film 2 is less than 20%, desired antistatic properties cannot be obtained.The antistatic film of the present invention has a small dependence of the surface resistance value on the film thickness. It is not necessary to control the film thickness so precisely to obtain a desired resistance value, and therefore, the film can be formed by a simple method such as spray coating or brush coating. The antistatic film has a desired and stable resistance value and can be favorably used in a vacuum atmosphere such as inside a vacuum envelope.

Next, as examples of an image display device having such an antistatic film, a cathode ray tube and a field emission display (FED) will be described with reference to the drawings.

As shown in FIG. 3, the color cathode ray tube according to the first embodiment has a glass panel 3 and an envelope including a funnel 4 and a neck 5. You. A phosphor screen 6 is formed on the inner surface of the panel 3, and a shadow mask 7 is arranged inside the panel 3 so as to face the phosphor screen 6. In order to improve brightness, contrast, emission chromaticity, etc., a color filter corresponding to the emission color of the phosphor (not shown) is provided between the phosphor screen 6 and the panel 3. Can be provided.

On the other hand, an electron gun 8 for emitting an electron beam 8a is arranged inside a glass neck 5. The antistatic film 9 is formed on the inner wall of the neck 5 so as to cover at least 20% of the entire inner wall, and the end is connected to a conductive layer (not shown). I have. An inner shield 10 is disposed inside the funnel 4 to shield the electron beam 8a emitted from the electron gun 8 from an external magnetic field, and an outer magnetic field is generated outside the funnel 4 by the generated magnetic field. A deflecting device 11 for deflecting the beam 8a is arranged.

In this color one cathode ray tube, on a glass substrate of the neck 5 internal wall, 1 0 consists ^{of 6} to the high-resistance fine particles having a specific resistance of 1 0 ⁹ Omega · cm, a stable desired properties (surface resistance Since the antistatic film 9 having the following value is formed, the orbital deformation of emitted electrons due to the application of a high voltage and the deterioration of display characteristics due to sparks in the tube or leak current do not occur.

In the FED according to the second embodiment of the image display device of the present invention, as shown in FIG. 4, the substrate 12 on the electron emission side and the substrate 13 on the light emission side are arranged in parallel at a predetermined interval. They are arranged facing each other, and the inside is kept at a high vacuum. In the substrate 12 on the electron emission side, a plurality of cold cathode type electron emission elements 14 are formed on a substrate such as silicon. The light-emitting side substrate 13 has a glass panel 15, and a phosphor screen 16 is formed on a surface of the glass panel 15 facing the electron-emitting device 14. Color filter corresponding to the emission color of the phosphor An evening (not shown) is provided.

In addition, in order to support the weight of the glass panel 15 and the like and the load applied to the silicon substrate and the like due to the atmospheric pressure, a space between the substrate 12 on the electron emission side and the substrate 13 on the light emission side is required. 7 are arranged. The spacer 17 has an insulating member 18 such as a flat plate (I-shaped cross-section), a cross-shaped cross-section, and an L-shaped cross-section. % Or more. The end of the antistatic film 19 is connected to a conductive layer (not shown).

In the FED of the second embodiment, the surface of the insulating substrate 1 8 forming the scan Bae colonel one 1 7, a high-resistance fine particles having a specific resistance of ^{^{1 0 6 ~ 1 0 9 Ω}} · cm As a result, since the antistatic film having stable and desired characteristics is formed, the orbital deformation of emitted electrons due to the application of a high voltage and the deterioration of display characteristics due to sparks in the tube or leak current do not occur.

Next, the present invention will be further described based on specific examples. All percentages are by weight.

Example 1

First, an antistatic dispersion A having the following composition (hereinafter referred to as dispersion A) was prepared.

Antimony pentoxide (pyrochlore crystalline form) (particle size: 20 nm)… 1.0% Ethanol 99.0% Dispersion A was added to the neck of a 15-inch single-cathode CRT (outer diameter 22.5 (mm) along the tube axis along a length of about 15 mm with a brush, and then heated and fired at a temperature of about 450 ° C to obtain a film thickness of 300 nm. Was formed.

As Comparative Example 1, an antistatic dispersion B (hereinafter, referred to as dispersion B) having the following composition was prepared, and this dispersion B was used in the same manner as in Example 1. Then, an antistatic film (100 nm thick) was formed on the inner wall surface of the neck of the empty cathode ray tube.

AT 0 (particle size 10 nm) 1.0%

On the surface of the particle size 5 0 nm of AT 0 microparticles, sol - coating layer consisting of S i 0 ₂ (thickness l nm) was formed by a gel method, producing the composite fine particles C (hereinafter, referred to as fine particles C.) did. The resulting Toko filtrate obtained by measuring the resistivity of the fine particles C, was 1 0 ⁸ Q 'cm.

Next, an antistatic dispersion D (hereinafter, referred to as a dispersion D) having the following composition was prepared using the fine particles C, and the dispersion D was used in the same manner as in Example 1 to prepare a dispersion. An antistatic film (film thickness: 150 nm) was formed on the inner wall surface of the neck of the cathode ray tube.

Fine particles C 1.0% Ethanol 99.0% Next, for the cathode ray tube having an antistatic film obtained in Examples 1 and 2 and Comparative Example 1, the compassance drift characteristics (change amount), spark in the tube The presence and absence of deterioration of the focus characteristics due to leakage current were examined. Table 1 shows the results of these evaluations.

【table 1】

As is clear from Table 1, the antistatic films obtained in Examples 1 and 2 were The color cathode-ray tube that is equipped with the cathode-ray tube has much better performance than the color cathode-ray tube obtained in Comparative Example 1 in terms of the compactness drift characteristics, the presence or absence of sparks in the tube, and the focus deterioration characteristics due to leakage current. . Example 3

The dispersion A prepared in Example 1 is applied by brush coating to the entire surface of a low-alkali glass FED sensor member, and then heated and fired at a temperature of about 450 ° C. As a result, an antistatic film having a thickness of 50 O nm was formed.

Next, an FED was assembled and manufactured by a known method using this spacer. That is, a rear plate having a plurality of field emission electron sources and a face plate having phosphor layers arranged and formed in a predetermined pattern are opposed to each other via a spacer having the above-described antistatic film. The FED was manufactured by arranging and sealing a side plate and the like to the periphery.

Further, as Comparative Example 2, an antistatic film was formed on the surface of a sensor member in the same manner as in Example 3 using the above-mentioned dispersion liquid B, and an FED was produced using the antistatic film.

Example 4

Using the dispersion D prepared in Example 2, an antistatic film was formed on the surface of a spacer member in the same manner as in Example 3, and an FED was produced using the antistatic film.

Next, with respect to the FEDs obtained in Examples 3 and 4 and Comparative Example 2, the shift characteristics of the bright spot of the electron beam, the presence or absence of a spark in the tube, and the presence or absence of a leak current were examined. Table 2 shows the results of these evaluations.

[Table 2] Example 3 Example 4 Comparative Example 2 Displacement of bright spots of electron beam and electron beam No No Partial Yes Spark in tube No No Partial Yes Focus deterioration due to leak current No No Yes Thus, the FED having the antistatic film obtained in Examples 3 and 4 was obtained in Comparative Example 2 in terms of the shift characteristics of the luminescent spot of the electron beam, the spark characteristics in the tube, and the presence or absence of the leak current. It is superior to a color cathode ray tube. Industrial applicability

As is clear from the above description, according to the antistatic dispersion of the present invention, the dependency of the resistance value on the film thickness and the environment is small, and the antistatic film having stable performance can be formed by spray coating or the like. It can be formed by a simple method such as brushing. The antistatic film of the present invention can be used in a vacuum atmosphere such as inside a vacuum tube.

Further, in the image display device of the present invention, the surface of the insulating member arranged in the vacuum envelope has a small dependence of the resistance value on the film thickness and environmental conditions, and has a stable antistatic property having a desired resistance value. Since the film is formed, the display characteristics are not degraded due to the orbital deformation of the emitted electrons due to the application of the voltage and the spark or leak current in the tube, and stable and good display characteristics are exhibited. Therefore, its industrial value is extremely large.

Claims

The scope of the claims

^{^{1. 1 0 6 ~ 1 0 9}} Ω · ο high resistivity particles having a specific resistance value of m, antistatic dispersion characterized by containing as a main component.

2. The high resistance particles, antistatic dispersion according to claim 1, characterized in that antimony pentoxide having a crystal structure of pyrochlore (S b ₂ 0 _5).

3. periphery of the high-resistance fine _{_{particles, S n0 2, ln 2 0}} 3, S b 2 0 5, Z n0 at least selected from ₂ core layer comprising one of the semi-conductive material and, the core layer _{formed, S i 0 2, T i} 0 2, a 1 2 0 3 s Z r 0 claims to feature in that it has at least selected from ₂ coating layer comprising one of the insulating material The antistatic dispersion according to 1.

4. The antistatic dispersion according to claim 1, wherein the high-resistance fine particles have a particle size of 5 to 100 nm.

5. a antistatic film formed on the surface of the insulating substrate to be held in a vacuum atmosphere, and a high resistance particles having a specific resistance of ^{^{1 0 6 ~ 1 0 9 Ω}} · cm mainly An antistatic film, characterized in that:

6. The high resistance fine particles, antimony pentoxide (S b ₂ 0 ₅₎ antistatic film according to claim 5, characterized in that a having a crystal structure of pyrochlore type.

7. The high-resistance fine particles, the _{_{_{S n0 2, ln 2 0 3}}} , S b 2 0 5, Z n 0 at least selected from ₂ and a core layer comprising one of the semi-conductive material, the core layer formed on the outer periphery, claims and _{S i 0 2, T i 0} 2, a 1 2 0 3, feature that it has a Z r 0 _both least selected from the covering layer consisting of one of the insulating material Item 6. The antistatic film according to Item 5.

8. The antistatic film according to claim 5, wherein the high-resistance fine particles have a particle size of 5 to 100 nm.

9. A vacuum envelope having a translucent panel and the inside is kept in a vacuum, a phosphor layer formed on an inner surface of the translucent panel, and disposed inside the vacuum envelope. An image display device comprising electron emission means,

An image display device, comprising: the antistatic film according to claim 5 on a surface of an insulating member arranged in the vacuum envelope.

10. The image display device according to claim 9, wherein the antistatic film has a thickness of 50 to 1,000 nm.

10. The image display device according to claim 9, wherein the antistatic film covers at least 20% of a surface area of the insulating member.